Superabsorbent polymers have been in use in disposable absorbent articles, such as diapers and bandages for many years. Such superabsorbent polymers are capable of absorbing many times their weight of water and body fluids and can retain such absorbed liquids under moderate pressure, as measured by absorption under load (AUL). These superabsorbent polymers have been used together with a batt of absorbent fibers, such as cellulose fibers, to absorb and hold the liquid within the product. The most common absorbent batt used in the diaper art is manufactured from fluffed wood pulp fibers, as disclosed in U.S. Pat. No. 2,788,003, hereby incorporated by reference. A densified paper-like surface layer also has been used in conjunction with an absorbent batt to improve "wicking" of the liquid to the absorbent batt, as disclosed in U.S. Pat. Nos. 3,612,055 and 3,938,522, both hereby incorporated by reference. The absorbent structure of the present invention is useful with or without the absorbent batt and/or wicking layers disclosed in the above-identified patents.
One of the biggest problems associated with the use of superabsorbent polymers in an absorbent product is that of preventing so called "gel blocking". When liquid contacts a superabsorbent material, the superabsorbent material swells extensively. If superabsorbent particles are held too closely together in the absorbent structure, swelling of one superabsorbent particle inhibits the swelling of an adjacent, contacting superabsorbent particle so that the swelling (gelled) superabsorbent material prevents (blocks) further penetration of the liquid into the structure, thereby preventing all of the available superabsorbent material from being efficiently utilized.
One effort to avoid "gel blocking" is disclosed in the Pieniak, et al. U.S. Pat. No. 4,500,315 wherein particles of superabsorbent material are dispersed randomly throughout an absorbent fibrous web containing absorbent fibers, such as cellulosic fibers and/or peat moss. The absorbent fibrous web is compressed, after incorporating the superabsorbent material, to densify the absorbent web and hold the superabsorbent material in place with adjacent, frictionally entangled contacting absorbent fibers. It is asserted in the Pieniak, et al. patent that the fibrous web sufficiently spaces the superabsorbent particles, and the particles are sufficiently small, such that swelling of one superabsorbent particle does not interfere with the absorption of liquid and swelling of adjacent superabsorbent particles. However, it has been found that due to the random, free positioning of the superabsorbent particles, some of the superabsorbent particles sometimes interfere with absorption and swelling of adjacent superabsorbent particles.
In accordance with the principles of the present invention, superabsorbent particles are fixed to a support structure that has a fixed but flexible configuration so that the superabsorbent particles adhered thereto also have definite, fixed positions, with known spacing between adjacent superabsorbent particles, thereby assuring little or no gel blocking.